SMIF container latch mechanism

ABSTRACT

The present invention includes a latch assembly, such as maybe useful for SMIF pods. SMIF pods are in general comprised of a pod door which mates with a pod shell to provide a sealed environment in which wafers may be stored and transferred. During wafer storage and transport, the pod door is typically held affixed to the pod shell by a latch assembly. When it is desired to separate the pod door from the pod shell, each latch must be actuated outwardly, to withdraw each engagement portion from the pod door, at which time the pod door may be separated. The present invention includes an improved such latch assembly.

CLAIM OF PRIORITY

[0001] This application claims priority to Provisional patentapplication Ser. No. 60/217,204, filed Jul. 10, 2000, entitled SMIFContainer With Latch Lock Mechanism.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to the transfer of workpieces suchas semiconductor wafers within a storage and transport pod, and inparticular to a latch locking mechanism preventing unwanted opening ofthe pod.

[0004] 2. Description of Related Art

[0005] A SMIF system proposed by the Hewlett-Packard Company isdisclosed in U.S. Pat. Nos. 4,532,970 and 4,534,389. The purpose of aSMIF system is to reduce particle fluxes onto semiconductor wafersduring storage and transport of the wafers through the semiconductorfabrication process. This purpose is accomplished, in part, bymechanically ensuring that during storage and transport, the gaseousmedia (such as air or nitrogen) surrounding the wafers is essentiallystationary relative to the wafers, and by ensuring that particles fromthe ambient environment do not enter the immediate wafer environment.

[0006] A SMIF system has three main components: (1) minimum volume,sealed pods used for storing and transporting wafers and/or wafercassettes; (2) an input/output (I/O) minienvironment located on asemiconductor processing tool to provide a miniature clean space (uponbeing filled with clean air) in which exposed wafers and/or wafercassettes may be transferred to and from the interior of the processingtool; and (3) an interface for transferring the wafers and/or wafercassettes between the SMIF pods and the SMIF minienvironment withoutexposure of the wafers or cassettes to particulates. Further details ofone proposed SMIF system are described in the paper entitled “SMIF: ATECHNOLOGY FOR WAFER CASSETTE TRANSFER IN VLSI MANUFACTURING,” by MihirParikh and Ulrich Kaempf, Solid State Technology, July 1984, pp.111-115.

[0007] Systems of the above type are concerned with particle sizes whichrange from below 0.02 microns (μm) to above 200 μm. Particles with thesesizes can be very damaging in semiconductor processing because of thesmall geometries employed in fabricating semiconductor devices. Typicaladvanced semiconductor processes today employ geometries which areone-half μm and under. Unwanted contamination particles which havegeometries measuring greater than 0.1 μm substantially interfere with 1μm geometry semiconductor devices. The trend, of course, is to havesmaller and smaller semiconductor processing geometries which today inresearch and development labs approach 0.1 μm and below. In the future,geometries will become smaller and smaller and hence smaller and smallercontamination particles and molecular contaminants become of interest.

[0008] SMIF pods are in general comprised of a pod door which mates witha pod shell to provide a sealed environment in which wafers may bestored and transferred. So called “bottom opening” pods are known, wherethe pod door is horizontally provided at the bottom of the pod, and thewafers are supported in a cassette which is in turn supported on the poddoor. It is also known to provide “front opening” pods, in which the poddoor is located in a vertical plane, and the wafers are supported eitherin a cassette mounted within the pod shell, or to shelves mounteddirectly in the pod shell itself.

[0009] In order to transfer wafers between a SMIF pod and a process toolin a bottom opening system, a pod is typically loaded either manually orautomatedly onto a load port on a front of the tool so that the pod doorlies adjacent the port door of the process tool. Thereafter, mechanismswithin the load port decouple the pod door from the pod shell and lowerthe pod door and port door together into the minienvironment, with awafer carrying cassette remaining seated on the pod door. The pod shellremains in position against the interface port to maintain a seal at theport and to define a sealed, clean environment including the interior ofthe process tool and pod shell. A wafer handling robot within theprocess tool may thereafter access particular wafers supported in thepod shell for transfer between the pod and the process tool.

[0010] During wafer storage and transport, the pod door is typicallyheld affixed to the pod shell by one of two different latch assemblies.In a first system, referred to herein as a perimeter latch assembly,four independently operated latches are mounted to a bottom perimeter ofthe pod shell, with an engagement portion of each latch extending inwardunder the pod door to maintain the pod door in a sealed position in thepod. When it is desired to separate the pod door from the pod shell,each of the four latches is actuated outwardly, to withdraw eachengagement portion from under the pod door, at which time the pod doormay be separated. Each of the latches needs to be actuated outward todisengage the pod door from the pod shell. In conventional perimeterlatch systems, the latches may be disengaged manually, or the pod may beseated on a load port or other support surface including four actuationpins. The pins fit into slots formed on each of the latches, and, afterthe pod is properly positioned on the support surface, the actuationpins move the each of the latches outward to withdraw the engagementportion of each latch from under the pod door. Thereafter, the pod doormay be separated from the pod shell.

[0011] A single latch of a perimeter latch lock assembly is shown inprior art FIG. 1. As explained above, a latch 20 is mounted on the lowerperimeter of pod shell 22, and includes an engagement portion 24extending under the pod door 26. The latch 20 may be actuated eithermanually or by means of a pin (not shown) on a support surface engagedwithin slot 28 so as to move to the left from the perspective of FIG. 1.Once the latch 20 is moved sufficiently so that engagement portion 24 isclear of the pod door (and the other latches are similarly actuated, thepod door may be separated from the pod shell. The latch may be biasedinto sealing position shown in FIG. 1 by a spring or other biasingscheme, such as leaf spring 30 shown in FIG. 1.

[0012] A second type of latch assembly (not shown) is disclosed in U.S.Pat. No. 4,995,430, entitled “Sealable Transportable Container HavingImproved Latch Mechanism”, to Bonora et al., which patent is owned bythe assignee of the present application. The mechanism disclosed thereinincludes a latch hub centrally mounted within the pod door, which latchhub engages with first and second translating latch plates. The latchplates include ends which extend beyond the footprint of the pod doorand into slots in the pod shell. When the latch plates are in anextended position, the ends fit into the slots in the pod shell to sealthe pod. When the latch plates are in a retracted position, the ends ofthe latch plates withdraw into the footprint of the pod door to allowseparation of the pod door from the pod shell. When a pod including thistype of latch assembly is mounted on a load port or other such supportsurface, mechanisms within the support surface rotate the hub to movethe latch plates between their extended and retracted positions.

[0013] In the perimeter latch assembly, it can happen that an operatormanually disengages each of the latches to open the pod when in fact thepod should not be opened. Such unwanted pod openings can lead tocontamination of the workpieces within the pod and/or an improperexchange of one workpiece lot for another within the pod.

BRIEF SUMMARY OF THE INVENTION

[0014] The present invention includes a latch mechanism for latching afirst member to a second member, such as a pod door to a pod shell in asemiconductor environment. The latch mechanism includes a latch lockmounted to the first member, comprising a finger portion and an angledportion. A latch is mounted to the first member, adapted to move betweena latched position and an unlatched position. The latch has anengagement portion that contacts a portion of the second member when thelatch is in the latched position, so as to maintain contact between thefirst and second members. The latch also has a slot for receiving thefinger of the latch lock. An actuation pin is positioned in the slot ofthe latch. The actuation pin is adapted move laterally between a firstposition and a second position. The actuation pin slidably contacts theangled portion, such that when the actuation pin moves between the firstposition and the second position the angled portion moves in a directionorthogonal to the lateral movement. This allows the finger portion tomove into and out of the slot. The latch may then be moved between thelatched and unlatched positions when the finger portion is notpositioned in the slot.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a prior art perspective view of a single latch of aperimeter latch assembly;

[0016]FIG. 2 is a partial bottom perspective view of a pod shellincluding a latch lock in accordance with one embodiment of the presentinvention;

[0017]FIG. 3 is a partial bottom perspective view of a pod including aperimeter latch and a latch lock in accordance with one embodiment ofthe present invention;

[0018]FIG. 4 is a perspective view of a pod including a perimeter latchin accordance with one embodiment of the present invention;

[0019]FIGS. 5A and 5B are bottom views of a pod including a perimeterlatch and a latch lock in accordance with one embodiment of the presentinvention;

[0020]FIGS. 6A through 6D are bottom views of a pod seated on a supportsurface including an actuation pin for moving a latch lock out oflocking position while opening the perimeter latch, in accordance withone embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0021] The present invention will now be described as referenced toFIGS. 2-6D which in preferred embodiments relate to a latch lock forlocking a perimeter latch in position to prevent unwanted opening of thepod. It is understood the type of pod is not critical to the presentinvention, and the pod may house various work pieces such assemiconductor wafers, reticles or flat panel displays. Moreover, while apreferred embodiment of the pod according to the present inventionoperates according to SMIF technology, it is understood that the presentinvention may be used with containers operating according totechnologies other than SMIF technology in alternative embodiments ofthe present invention.

[0022] Referring now to FIG. 2, there is shown a bottom perspective viewof a pod shell 100 including a latch lock 102 according to the presentinvention. Latch lock 102 may be formed between an inner wall 100 a andan outer wall 100 b on the pod shell 100, and may be injection molded aspart of the pod shell The latch lock 102 may be formed of variouspolymers including polycarbonate and acrylonitrilebutadiene-styrene(ABS). Although one such latch lock 102 is shown in FIG. 2, it isunderstood that there is preferably one latch lock for each perimeterlatch on the pod. Thus, there are preferably 4 latch locks. Thefollowing description applies to each of the latch locks. It isunderstood that there may be less latch locks than perimeter latches inalternative embodiments.

[0023] Latch lock 102 includes a first portion 104 having a finger 106which represents the lowest point on the latch lock when held in itsnormal position facing downward. Latch lock 102 further includes asecond, angled portion 108 which angled with respect to first portion104 for purposes as will be explained hereinafter. The latch lock 102may be approximately three-quarters of an inch in length and may beflexible so as to deflect as explained hereinafter. It is understoodthat the latch lock 102 may be longer or shorter than three-quarters ofan inch in alternative embodiments.

[0024] Referring to FIG. 3, there is shown a bottom view of a podincluding a pod shell 100 and a pod door 110 which together define asealed environment (not shown) for a work piece within a container. FIG.3 further shows a perimeter latch 112 mounted to pod shell 100 via aleaf spring 114. Perimeter latch 112 is preferably of conventionaldesign. As shown in FIG. 4, leaf springs 114 attach to the pod shell andflex to allow perimeter latch 112 to move between an unbiased positionshown in FIG. 3 and a flexed position shown for example in FIG. 6D inwhich the latch 112 allows the pod door 110 to be removed (While FIG. 4shows a reticle pod, as explained above, the container including a latchlock according to the present invention may house various workpieces).

[0025] Latch 112 further includes an engaging portion 116 which extendsunder a portion of the pod door 110 so as to maintain the pod door 110sealed within the pod. Latch 112 additionally includes a slot 118 forreceiving an actuation pin 120 (explained hereinafter with respect toFIGS. 6A-6D) and for receiving the finger 106 of latch lock 102.

[0026] Referring now to FIGS. 5A and 5B, finger 106 extends into slot118 so that, if an attempt is made to manually move latch 112 to aposition free of the pod door, finger 106 abuts against a portion of thewall defining slot 118 as shown in FIG. 5B to prevent the engagementportion 116 from moving clear of the pod door 110. Thus, the latch lock102 according to the present invention prevents unwanted separation ofthe pod door from the pod shell.

[0027] On the other hand, referring to the bottom view of FIGS. 6Athrough 6D, when the pod is located on a support surface (not shown), anactuation pin 120 seats in slot 118. Once the pod is properly positionedon a support surface, a motor beneath the support surface actuates thepins laterally outward (to the right from the perspective of FIGS.6A-6D). Upon moving laterally, in addition to moving the latch 112,actuation pin 120 bears against the angled portion 108 (FIGS. 2 and6A-6D) so as to deflect latch lock 102 and finger 106 downward from theview shown in FIGS. 6A-6D (i.e., substantially perpendicular to themovement of the actuation pin 120). In moving downward, the finger 106moves out of slot 118 and no longer prevents the latch 112 from movinglaterally so that the engagement portion 116 may move clear of the poddoor as shown in FIG. 6D.

[0028] As is further shown in FIG. 6D, once the latch 112 is movedlaterally to free the pod door from the pod, the actuation pin 120 alsomoves clear of the latch lock 102. At this point, the latch lock movesback to its unflexed position. Thus, while the pod door is clear of thepod during processing of the workpiece(s), the latch lock is unflexed soas to minimize fatigue on the latch lock. When in the position shown inFIG. 6D, the finger 106 resides in a detent formed on the top side ofthe perimeter latch (shown in phantom in the bottom views of FIGS. 6Athrough 6D). The finger 106 abuts against the wall of the slot 118 andis prevented from entering this detent unless the finger is firstdeflected downward by the actuation pin 120 at the same time theperimeter latch 112 moves laterally.

[0029] After processing of the work pieces within the pod is completed,and the pod door is returned to its mated position with the pod shell,the actuation pins 120 may move the latch 112 back to its couplingposition (i.e. the engagement pin 120 moves to the left with respect tothe views shown in FIGS. 6A-6D). When the actuation pin 120 begins itslateral movement to the left from the perspective of FIGS. 6A through6D, the finger 106 is again deflected downward by the pin 120 as theperimeter latch is moved to the left so that the finger can once againseat within the slot 118 (FIG. 6A). Once returned to this home position,the actuation pins 120 no longer contact the angled portion 108 of thelatch locks 102 so that the latch locks 102 return to their undeflectedposition.

[0030] Although the invention has been described in detail herein, itshould be understood that the invention is not limited to theembodiments herein disclosed. Various changes, substitutions andmodifications may be made thereto by those skilled in the art withoutdeparting from the spirit or scope of the invention.

What is claimed is:
 1. A latch mechanism for latching a first member to a second member, said latch mechanism comprising: (a) a latch lock mounted to said first member, said latch lock comprising: (i) a finger portion; and (ii) an angled portion angled with respect to said finger portion; (b) a latch mounted to said first member, said latch adapted to move between a latched position and an unlatched position, said latch comprising: (i) an engagement portion adapted to contact a portion of said second member when said latch is in said latched position so as to maintain contact between said first member and said second member; and (ii) a slot for receiving said finger of said latch lock; and (c) an actuation pin positioned in said slot of said latch and adapted move laterally between a first position and a second position, said actuation pin adapted to slidably contact said angled portion such that when said actuation pin moves between said first position and said second position said angled portion moves in a direction orthogonal to the lateral movement such that said finger portion is moved into and out of said slot, said latch adapted to move between said latched and unlatched positions when said finger portion is not positioned in said slot.
 2. A latch mechanism according to claim 1, further comprising a spring adapted to mount said latch to said first member.
 3. A latch mechanism according to claim 2, wherein said spring is a leaf spring.
 4. A latch mechanism according to claim 2, wherein said spring is adapted to allow said latch to move between said latched and unlatched positions, said spring being flexed when said latch is in said unlatched position.
 5. A latch mechanism according to claim 1, wherein said slot has a wall portion, and said finger portion is adapted to contact said wall portion to prevent said engagement portion from losing contact with said second member when said finger portion is in said slot.
 6. A latch mechanism according to claim 1, further comprising a support surface for supporting said first and second members.
 7. A latch mechanism according to claim 6, wherein said actuation pin is mounted to said support surface.
 8. A latch mechanism according to claim 6, further comprising a motor adapted to drive the lateral movement of said actuation pin.
 9. A latch mechanism according to claim 1, wherein said actuation pin is further adapted to move clear of said latch when said finger portion is out of said slot.
 10. A latch mechanism according to claim 9, wherein said latch lock is adapted to move back to said latched position when said first and second members are not in contact.
 11. A latch mechanism for latching a door to a container, said latch mechanism comprising: (a) a latch lock mounted to said container, said latch lock comprising: (i) a finger portion; and (ii) an angled portion angled with respect to said finger portion; (b) a latch mounted to said container, said latch adapted to move between a latched position and an unlatched position, said latch comprising: (i) an engagement portion adapted to contact a portion of said door when said latch is in said latched position so as to maintain contact between said door and said container and (ii) a slot for receiving said finger of said latch lock; and (c) an actuation pin positioned in said slot of said latch and adapted move laterally between a first position and a second position, said actuation pin adapted to slidably contact said angled portion such that when said actuation pin moves between said first position and said second position said angled portion moves in a direction orthogonal to the lateral movement such that said finger portion is moved into and out of said slot, said latch adapted to move between said latched and unlatched positions when said finger portion is not positioned in said slot.
 12. A latch mechanism according to claim 11, further comprising a spring adapted to mount said latch to said container and allow said latch to move between said latched and unlatched positions, said spring being flexed when said latch is in said unlatched position.
 13. A latch mechanism according to claim 11, wherein said slot has a wall portion, and said finger portion is adapted to contact said wall portion to prevent said engagement portion from losing contact with said door when said finger portion is in said slot.
 14. A latch mechanism according to claim 11, further comprising a support surface for supporting said container.
 15. A latch mechanism according to claim 14, wherein said actuation pin is mounted to said support surface.
 16. A latch mechanism according to claim 11, further comprising a motor adapted to drive the lateral movement of said actuation pin.
 17. A latch mechanism according to claim 11, wherein said container has an inner wall and an outer wall, and said latch lock is formed between said inner wall and said outer wall of said container.
 18. A latch mechanism according to claim 11, wherein said latch lock is molded as part of the container.
 19. A latch mechanism according to claim 11, wherein said latch lock is comprised of a polymer.
 20. A latch mechanism according to claim 19, wherein said polymer is selected from the group consisting of polycarbonate and acrylonitrile-butadiene-styrene (ABS).
 21. A latch mechanism according to claim 11, wherein said latch lock is approximately three-quarters of an inch in length.
 22. A latch mechanism according to claim 11, wherein said door and said container define a sealed environment.
 23. A latch mechanism for latching a pod door to a shell of a pod adapted to contain a workpiece, said latch mechanism comprising: (a) a latch lock mounted to said shell, said latch lock comprising: (i) a finger portion; and (ii) an angled portion angled with respect to said finger portion; (b) a perimeter latch mounted to said shell, said perimeter latch adapted to move between a latched position and an unlatched position, said perimeter latch comprising: (i) an engagement portion adapted to contact a portion of said pod door when said perimeter latch is in said latched position so as to maintain contact between said pod door and said shell; and (ii) a slot for receiving said finger of said latch lock; and (c) an actuation pin positioned in said slot of said perimeter latch and adapted move laterally between a first position and a second position, said actuation pin adapted to slidably contact said angled portion such that when said actuation pin moves between said first position and said second position said angled portion moves in a direction orthogonal to the lateral movement such that said finger portion is moved into and out of said slot, said latch adapted to move between said latched and unlatched positions when said finger portion is not positioned in said slot.
 24. A latch mechanism according to claim 23, further comprising a spring adapted to mount said perimeter latch to said shell and allow said perimeter latch to move between said latched and unlatched positions, said spring being flexed when said perimeter latch is in said unlatched position.
 25. A latch mechanism according to claim 23, further comprising a support surface for supporting said pod.
 26. A latch mechanism according to claim 23, wherein said actuation pin is mounted to said support surface.
 27. A latch mechanism according to claim 23, further comprising a motor adapted to drive the lateral movement of said actuation pin.
 28. A latch mechanism according to claim 23, wherein said pod defines a sealed environment.
 29. A latch mechanism according to claim 23, wherein said workpiece is selected from the group consisting of semiconductor wafers, reticles, and flat panel displays.
 30. A latch mechanism according to claim 23, wherein said pod operates according to SMIF technology.
 31. A latch mechanism according to claim 23, wherein said pod comprises multiple said latch mechanisms. 